1. Field of the Invention
The invention relates to a support beam unit intended for the support of at least one functional unit in a machine for the production and/or the processing of a material web, specifically a paper or cardboard web.
2. Description of the Related Art
During the operation of machinery for the production and/or processing of a fiber material web, specifically a paper or cardboard web, functional units, such as for example metering devices, together with the support beams on which the functional units are mounted are subject to a multitude of different stresses. Mechanical stresses due to the ever present elasticity which exists in the materials used in the construction of the support beams or the functional units, i.e. steel, and thermal stresses caused by thermal expansions lead to deflections of the support beam and the functional unit. Such deflections cause irregularities in the progression of the process, thereby negatively influencing the process result.
A certain improvement with regard to the deflection of the support beam and the functional device may be achieved by appropriately locating or supporting the support beam which is supporting the functional unit. A support beam known from DE 296 00 016 U is supported at two locations, whereby these points of support are located in the longitudinal direction of the support beam, at a certain distance from the two ends of the support beam. To achieve an additional reduction in the support beam deflection, the support beam may be equipped with a compensating device, for example, pressure tubing extending along the interior of the supporting beam, parallel to its longitudinal axis. Based on the placement of the supporting beam as suggested in DE 296 00 016 U, a more favorable deflection line is achieved with regard to mechanical stress of the supporting beam. It is, however, a disadvantage that the suggested placement is unsuitable for supporting beams manufactured from materials having a low thermal expansion factor. Supporting beams manufactured from materials that offer thermal dimensional stability, for example, glass or carbon fiber reinforced synthetics, have hitherto proven to be insufficiently deflection resistant.
Therefore, the current invention provides a construction method enabling utilization of materials that offer thermal dimensional stability for the manufacture of supporting beams in the aforementioned types of machinery.
According to the current invention, a support beam unit for supporting at least one functional device in a machine for the production and/or processing of a fiber material web, specifically a paper or cardboard web, includes a first partial supporting beam and a second partial supporting beam. The first partial supporting beam supports the functional device and is supported on the second partial supporting beam. The first partial supporting beam surrounds the second supporting beam, at least sectionally.
The method of construction suggested by the current invention allows a division of the stability functionalities between the first and the second partial supporting beam. In one embodiment, the first partial supporting beam is manufactured from a thermally dimensionally stable material, for example, a fiber reinforced synthetic material, preferably fiber glass or carbon fiber reinforced synthetics. Meanwhile, the second partial supporting beam is configured so that, in addition to the thermal dimensional stability provided by the first partial supporting beam, the entire supporting beam unit also has the necessary mechanical rigidity and flexural strength.
The second partial supporting beam may be manufactured from steel, preferably rust-resistant steel and/or from a fiber reinforced synthetic material, preferably a glass fiber or carbon fiber reinforced synthetic material. Particularly when utilizing synthetic materials in the construction of the second partial supporting beam, a weight reduction can be achieved compared to conventional supporting beam construction, while attaining a sufficient flexural strength, due to the lower density of fiber reinforced synthetics.
In order to ensure longevity of the functional device under the conditions that are present in machinery for the production and/or processing of a fiber material web, it is advantageous to manufacture the functional unit from steel, preferably rust-resistant steel.
The generally limited space available in machinery of the aforementioned type can be utilized effectively if the longitudinal axes of the first partial support beam and the second partial support beam, at least in a non-deformed condition, are arranged essentially parallel to each other in an area of mutual extension.
A further improvement in the dimensional stability of the support beam unit is possible by supporting the first partial supporting beam on the second partial supporting beam on at least two supports which are arranged in longitudinal direction of the first partial support beam, preferably always at a predetermined distance from each end face of the first partial supporting beam. By supporting the first partial supporting beam on the second partial supporting beam in this manner, a favorable deflection characteristic of the first partial supporting beam can be achieved.
Particularly, with a uniform load on the support beam unit and the functional device supported on it, across the working width of the material web, as is desirable in machinery for the production and/or processing of material webs, it can be advantageous that the two or more supports are located symmetrically to the longitudinal center of the first partial supporting beam in longitudinal direction of the first supporting beam. By arranging the support locations symmetrically, identical support forces occur at the support locations due to a constant load across the working width of the material web, resulting in a symmetrical and thereby generally uniform load upon the entire supporting beam unit. This, in turn, has a positive effect on the process result. It has been proven to be especially effective if the distance of at least one of the supports from the allocated face end of the first partial supporting beam is between approximately 15% and approximately 30%, preferably approximately 25% of the length of the first partial supporting beam. It is, however, also feasible to arrange the supports asymmetrical relative to the longitudinal center.
In consideration of a load situation that is changeable, locally and/or chronologically, an adjustment of the supporting situation of the first partial supporting beam on the second partial supporting beam may be desirable according to prevailing load situation. For this purpose, the position of one or more of the supports may be adjustable transversely to the material web. A control device that is one or more of mechanically, electrically, and fluidly adjustable may be provided to allow for such an adjustment.
When considering a load dependent deflection line, both the line progression and the maximum deviation of the deformed profile from the desired profile occurring at one point are factors. This maximum deflection can be reduced by supporting the first partial supporting beam with one or more pairs of supports on the second partial supporting beam.
The fundamental principle of this type of support is already known, for example, from DE 196 136 184 A1. This prior publication describes the reduction in the deflection of a beam by use of absorbing forces at two separately configured rigid frames, whereby each of these is supported by a pair of supports at one end of the beam. However, it is not clear exactly at what location on the beam and frame unit the forces originating from a functional unit and the forces originating from the support on a machinery frame will act. It is, however, disadvantageous in every instance that the actual support includes two additional components which are manufactured separately and which must be installed keeping within low error tolerances. In comparison, the design principle of the current invention provides only one unit, that is the unit created by the two partial supporting beams.
As is the case with the two or more supports and depending on the load requirements, the two or more support pairs may also be located in the longitudinal direction of the first partial supporting beam and symmetrically to the longitudinal center of the first partial supporting beam. As previously described, a completely uniform load may be supplied to the support beam unit, for example, in the instance of a constant load across the working width of the material web. Depending on each specific load situation, the deflection line of the first partial support beam may be positively influenced by positioning the two supports of the one or more support pairs relative to the longitudinal axis of the first partial support beam, essentially at the same longitudinal position or at different longitudinal positions.
During operation the support beam unit must, on the one hand, be able to be supported securely and, on the other hand, be able to be positioned and/or aligned precisely. Therefore, one or more of the supports may be designed and/or arranged so that it can transfer forces and/or moments from the first partial support beam to the second partial support beam, and vice versa. This relates especially to the transfer of forces from the functional device in the direction of the moving background, as well as transfer of moments around the longitudinal direction of the first partial support beam, since forces and/or moments in these flow directions favor the adjustment of the functional device mounted on the supporting beam relative to the moving background.
In this context it can be desirable to prevent a distortion of the first partial support beam and the second partial support beam relative to each other in order to achieve high stability, in combination with the heretofore described precise positioning and orientational capabilities. In general terms this may relate to a distortion of the first partial support beam relative to the second partial support beam in all three directions in space. Since a distortion of the first partial supporting beam relative to the second partial supporting beam around its longitudinal axis has particularly undesirable effects on the process result, one will generally give priority to attempting to avoid this type of distortion.
In addition to static and quasi-static loads, dynamic loads such as vibrational forces may affect the supporting beam unit during operation. In order to improve or guarantee the process result, one or more support may include one or more damping elements. The damping element, which would preferably be manufactured from a synthetic material, may, for example, serve to reduce or suppress irregularities such as shocks and vibrations in the flow direction between the first partial support beam and the second partial support beam, thereby improving the positional stability of the first partial support beam carrying the functional device, relative to outside influences.
To avoid overloading of the damping element, one or more supports can each include one or more elements which, in relation to the elasticity of the damping element, is essentially rigid and which works together with the damping element for the support of the first partial support beam on the second partial support beam. For example, the damping element and the rigid element can be arranged side be side so that support of the first partial support beam on the second partial support beam initially occurs through the damping element and, following a certain marginal deformation of this damping element, occurs through the rigid element.
As previously mentioned, the repositioning or reorientation of the support beam unit can be expediently accomplished if the second partial support beam is mounted so that it can be rotated and/or pivoted around an axis that is located essentially parallel to the longitudinal axis of the first partial support beam. Since the repositioning of the support beam unit also results in repositioning of the functional device, the rotational and/or pivoting axis of the second partial support beam may essentially coincide with an adjustment line along which the functional device is adjusted relative to the moving background in order to obtain adjustment kinematics favorable to the function of the general arrangement. The functional device may be a metering unit, for example, a doctor blade, a metering rod and/or an air brush. If, for example, the functional unit is a doctor blade, it would be advantageous if the adjustment line progresses through the tip of the doctor blade.
Efficient utilization of the available space can be achieved if one end each of the second partial support beam rests on the operator side and the drive side of the machine.
To compensate for load related deformations in the supporting beam unit, as well as for the targeted adjustment of the operational conditions, such as, for example, the adjustment angle and pressure, the supporting beam unit may work together with one or more adjustment or positioning devices. Advantageously, the adjustment and positioning device operates together only with the second partial supporting beam, so as not to directly load additional adjustment forces on the first partial supporting beam carrying the functional device.
With a view to testing, maintenance and repairs, as well as for the purpose of mounting of functional elements on the second partial supporting beam, the first partial supporting beam may be equipped with openings in its longitudinal direction, through which the second partial supporting beam may be accessed. Such an opening would permit, for example, a control element for the adjustment and/or positioning device to work together with the second supporting beam in the area of its longitudinal center or in the area of at least one support location. Depending on the specific load situation and available space, this would ensure favorable development of a force of the positioning and/or adjustment device upon the second partial supporting beam. However, it is also feasible that an influence of an adjustment and/or positioning device control element upon the aforementioned locations is not desirable or possible. In such an instance a control element of this type could then work together with the second partial support beam in the area of one or more of its support locations. A control element could then, if necessary, through gearing, introduce a torque into the second partial support beam at its support location, to rotate it around an axis through both support locations of the second partial support beam. Movable support of the second partial supporting beam is also feasible, creating the possibility of compensating deformation of the support beam unit not only with respect to rotation but also translational motion.
In order to achieve a supporting beam unit with high mechanical stability that has a total weight that is as low as possible, the second partial supporting beam may be tubular, at least in sections thereof. Additionally, the outer profile of the second partial supporting beam may be approximated to the inside profile of the first partial supporting beam, at least in the area of common extension, in order to improve the rigidity of the arrangement.
Compensation of load related supporting beam unit deformations can be simplified considerably or even automated if the adjustment and/or positioning device also includes a data acquisition device to record a displacement of the functional unit resulting from deflection of the second partial support beam; as well as a plotting unit which, based on the signals recorded by the acquisition device, determines actuating signals for the one or more control elements. An effective and precise compensation of the load-related support beam deformations is, for example, possible if the adjustment and/or positioning unit includes a device for measuring operational conditions which would measure the actual operational condition of the machine, for example, based on parameters of machine speed and line compression of the functional unit, the support beam unit and/or similar units and the plotting unit can continue to determine an actuating signal for the one or more control elements, based on the operational condition that was measured by the operational condition measuring device.
A suitable method for controlling the position and/or orientation of the support beam unit may include the following steps:
measuring the displacement of the functional unit due to deflection of the second partial support beam by using a measuring device;
determining actuating signals by using a plotting device and using the signals acquired by the measuring device; and
positioning the support beam unit according to the determined actuating signals.